NAME

dsttrf - compute the factorization of a symmetric tridiagonal matrix A

SYNOPSIS

SUBROUTINE DSTTRF( N, L, D, SUBL, IPIV, INFO )

INTEGER INFO, N

DOUBLE PRECISION D( ∗ )

DOUBLE PRECISION L( ∗ ), SUBL( ∗ )

#include <sunperf.h>

void dsttrf(int n, double ∗l, double ∗d, double ∗subl, int ∗info) ;

PURPOSE

DSTTRF computes the factorization of a complex Hermitian tridiagonal matrix A. 
 

ARGUMENTS

N (input) INTEGER
The order of the matrix A.  N >= 0.

L (input/output) DOUBLE PRECISION array, dimension (N)
On entry, the n-1 subdiagonal elements of the tridiagonal matrix A.  On exit, part of the factorization of A.

D (input/output) DOUBLE PRECISION array, dimension (N)
On entry, the n diagonal elements of the tridiagonal matrix A.  On exit, the n diagonal elements of the diagonal matrix D from the L∗D∗L∗∗T factorization of A.

SUBL (output) DOUBLE PRECISION array, dimension (N)
On exit, part of the factorization of A.

IPIV (output) INTEGER array, dimension (N)
On exit, the pivot indices of the factorization.

INFO (output) INTEGER
= 0:  successful exit
< 0:  if INFO = -i, the i-th argument had an illegal value
> 0:  if INFO = i, D(k,k) is exactly zero.  The factorization has been completed, but the block diagonal matrix D is exactly singular and division by zero will occur if it is used to solve a system of equations.

SunOS 5.0  —  Last change: 10 Dec 1998